How Do Squids Make Ink?

Squids are cephalopods, and they have an ink sack that contains melanin, which can be shot out through a propulsion system. Learn about the mucus membrane that surrounds a squid's ink sack with help from a science teacher and field biologist in this free video on biology.

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Video Transcript

Hi, I'm Brian with ericksontutoring.blogspot.com. And today we're going to discuss how squids make ink. So squids are a type of cephalopod, and so cephalopods also include organisms like clams, mollusks, octopuses, cuddle fish, those kind of things. And so all, all colloids I believe is how they're pronounced, so that's octopuses, squids and cuddle fish, except for the deep water ones, have something called an ink sack. And the ink sack is below their gut and it's right next to their anus and basically inside of the ink sack you have melanin and melanin is just a dark pigment. And so they have this sack and if they get startled or there's a predator, they can eject all the melanin inside the ink sack. It gets shot out with the jet propulsion that they use to move around and so there's ink, it is shooting out their backside. And it has a mucus membrane around it. So it sort of retains the shape and size of the squid, but at the same time the squid's already disappearing. So, the ink sack and the propulsion system are how squids make ink.